#ifndef SALES_DATA_HPP
#define SALES_DATA_HPP

#include <iostream>
#include <string>

class Sales_data
{
    friend std::istream& operator >> (std::istream&, Sales_data&);
    friend std::ostream& operator << (std::ostream&, const Sales_data&);
    friend bool operator < (const Sales_data&, const Sales_data&);
    friend bool operator == (const Sales_data&, const Sales_data&);

    public:
        Sales_data() = default;
        Sales_data(const std:: string &book): bookNo(book){}
        Sales_data(std::istream &is)
        {
            is >>*this;
        }

    public:
        Sales_data& operator += (const Sales_data&);
        std:: string isbn() const{ return bookNo;}

    private:
        std:: string bookNo;
        unsigned units_sold = 0.0;
        double sellingprice = 0.0;
        double saleprice = 0.0;
        double discount = 0.0;
};

inline bool compareIsbn(const Sales_data &lhs, const Sales_data &rhs)
{
    return lhs.isbn() == rhs.isbn();
}

Sales_data operator + (const Sales_data&, const Sales_data&);

inline bool operator == (const Sales_data &lhs, const Sales_data &rhs)
{
    return lhs.units_sold == rhs.units_sold &&
        lhs.sellingprice == rhs.sellingprice &&
        lhs.saleprice == rhs.saleprice &&
        lhs.isbn() == rhs.isbn();

}

inline bool operator != (const Sales_data &lhs, const Sales_data &rhs)
{
    return !(lhs == rhs); 
}

Sales_data & Sales_data::operator += (const Sales_data& rhs)
{
    units_sold += rhs.units_sold;
    saleprice = (rhs.saleprice * rhs.units_sold + saleprice * units_sold) / (rhs.units_sold + units_sold);
    if (sellingprice!= 0)
    {
        discount = saleprice / sellingprice;
    }
    return *this;
}

Sales_data operator + (const Sales_data& lhs, const Sales_data& rhs)
{
    Sales_data ret(lhs);
    ret += rhs;
    return ret;

}

std::istream& operator>>(std::istream& in, Sales_data& s)
{
    in >> s.bookNo >> s.units_sold >> s.sellingprice >> s.saleprice;
    if (in && s.sellingprice != 0)
    {
        s.discount = s.saleprice / s.sellingprice;
    }
    else 
        s = Sales_data();
    return in;
}

std::ostream& operator << (std::ostream& out, const Sales_data& s)
{
    out << s.isbn()<< " " << s.units_sold << " " 
        << s.sellingprice << " " << s.saleprice << " "
        << s.discount;
    return out;
}
#endif
